Repairing Septic Tank line

[LazyPup]

I received this question from one of our new members via a personal message however I feel that the question would be of interest to all, therefore I am posting this in the open forum for all to see.

Quote:
I hope you dont mind me contacting you, but after browsing the web for an answer to my problem I came accross your posts and found them very helpful, and wondered if you could shhed some light on my problem.

Recently purchased an old house that has a septic tank for sewerage. After lots of bad smells, leaks into basement I have dug up and exposed the pipe leading to the tank.

I have discovered a hole in the underside of the cast iron pipe about a 4 inches before it eneters the tank.

I am guessing the best bet is to replace the cast iron pipe with PVC pipe (Sched 40?).

I was only going to replace a section of the pipe about 3/4 feet as the rest of the cast iron pipe seems pretty solid and I dont really want to have to work on feeding a whole new pipe from the basement.

My main areas of concern are:

How to connect the new PVC pipe to old cast iron. Some info I have found suggests using donuts, others epoxys. Do I use purple primer?

Another huge area of concern is where to remover the cast iron pipe at the tank. Does that pipe inter the tank a bit, or is it flush with the exterior wall. at present the cast iron pipe is surrounded by concrete or a putty or something (my apologies, as youcan gather I am pretty clueless!!). Does that all need to be removed.

Also, what would be the best way for me to connect the new PVC pipe to the tank. Is there a putty, or do you use quikrete as I saw somewhere.

Thank you so much for taking the time to read this. Any advice would be grately received
Sincerely

[LazyPup]

Although it is almost never used today, originally cast iron pipe DWV pipe and Vitreous Clay sewer pipe was what is known as "Hub & Spigot pipe". Each section of pipe or fittings have a female hub on the input (upstream end) and the discharge (downstream) end it has a "male" raw pipe diameter.

Traditionally they would begin laying the pipe at the septic tank or municipal sewer location and work backwards toward the structure. The male "spigot end" of each section of pipe is inserted into the female "hub" of then the space between the exterior wall of the male pipe and the interior wall of the female hub was packed half full of a fibrous hemp material called "oakum".which looks like frayed rope that has been saturated in a tar like substance. When the oakum was firmly packed in place the joint was then capped off with molten lead.

The plumbing codes no longer permit the use of lead to make pipe joints.

For new construction, when cast iron pipe is specified we use a type of cast iron pipe known as "No-Hub pipe" No hub pipe is straight cast iron pipe with a raw pipe end (spigot) one each end and it is connected by means of "Mission Band" clamps. Mission band clamps are simply a neoprene sleeve with an outer metal sleeve surrounding the neoprene sleeve, and held in place by screw down spring clamps similar to the radiator hose clamps used in the automotive trade.

Repairing your sewer line is a fairly easy job. The first task is to remove the defective section of pipe. Fortunately cast iron pipe is very brittle and can easily be broken out by holding a heavy hammer tight against the pipe wall on one side and hitting the opposite side of the pipe with a second heavy hammer. (i use two 3lb hand sledge hammers). Careful here, cast iron pipe is brittle and shards may fly off as it breaks. i strongly advise you to wear good quality leather work gloves and goggles when shatter cast iron pipe out.

One you have the defective section broken out you will have a raw spigot end on the cast iron pipe and there should be a cast hub in the wall of the septic tank. (see illustration).

Measure the distance from the bottom of the hub in the septic tank wall to the end of the cast iron pipe and cut a length of schedule 40 PVC pipe about 1/2" less.

Insert a "Fernco' neoprene donut into the hub of the septic tank wall and slip a "Fernco CI coupling on one end of the PVC pipe.

Now align your section of PVC with the Fernco coupling on the cast iron pipe end. (upstream end) and insert the opposite end into the donut in the tank wall. You can then align the upstream end of the PVC with the cast iron pipe, slip the Fernco over the joint and tighten the clamps.

NOTE- Be sure you use Schedule 40PVC pipe. PVC pipe is used for both pressure piping and DWV (drain, waste & vent) applications however, PVC pipe used for pressure piping is made in sched. 20, sched,30,sched.40, sched.80 sched.120 and sched.200when used for pressure pipe the pipe has to be certified as suitable under ASTM D-1785.

For DWV (drain, waste and vent) applications all PVC pipe MUST BE schedule 40 and certified under ASTM D-2665. Fortunately all sched.40 pipe is labeled as certified under both ASTM D-1785 & D-2665.

[Redwood]

Plumbing code does not prohibit poured lead joints however, with the modern materials there are very few plumbers today who even would know how to pour a lead joint. The last time I used my lead pot I was pouring fishing sinkers and lead balls for my cap and ball blackpowder rifle. It is a dying art. There are still some locations where no hub is not permitted and lead joints are still reigning supreme. Mostly large cities with a heavy union membership in the plumbing field.

You could also cut the pipe with a carbide grit or Diamond blade in a sawzall or a diamond blade in a angle grinder. This may limit the need to replace a whole section. A chain snapper may be used but often with older cast iron pipe it is not quite as good as you think it is and the chain snapper will crush the pipe.

Some areas may reguire the use of a banded coupling to join the cast iron and PVC pipes together. Check with your local plumbing inspector.



Also the connection to the septic tank may have specific requirements again check with your local inspector.

On another note I would not dig the hole any deeper than absolutly necessary to eliminate any settling problems that may occur. It is veryy important that the soil under the pipe stays compacted.

[jnaas2]

When I took my Plumbing test they still had us pour a lead joint, Havent poured one since, Thanks for the fernco they save a lot of work. Diamond blade in a 4 inch grinder will cut thru cast iron like its butter